Flat decks account for approximately 50% or more of the roofing market for large industrial and commercial buildings which quite typically have flat or near flat roof surfaces. These roof surfaces generally are multi-layered, that is, they generally have in combination a roof supporting structure which is surmounted by a deck, and at least one layer of air or water impermeable membrane (barrier film or layer), thermal insulation, usually in plank form, and generally a ballast layer. These types of roofs tend to be economical and function quite well as long as there is no break in the water-impermeable membrane. Once the water-impermeable membrane is broken, water enters the roof system and seeps and runs randomly, and laterally between the various layers, soaking the roofing materials and the water eventually enters the interior of the building at points with no obvious relationship to the break in the water barrier layer. When this happens, the roof must be repaired, but often, one cannot detect where the membrane is broken and hence cannot effectively undertake repairs.
Commensurate with the leak problem is the desire to prevent excess air from moving from the interior of the building into the roof assembly and getting beneath the water-impermable membrane which could lead to wind blow off of the roof system. Therefore, it is desirable to have some air escape from inside the roof assembly to the exterior. Thus, it would be desirable to have a system for allowing a limited amount of water to pass downward, and only a limited amount of air to move upward. It would also be most desirable to limit the amount of water and air without compromising the holding capabilities of a penetrating device in those cases where the leak localizers of the instant invention are also fasteners. Having the above described capabilities of holding down roofs has the benefit of lowering the costs of the installation of such roofs. Thus, it would be a benefit if the system used to localize and detect leaks in the roof could act as a more or less permanent system to also hold down the roof system.
The inventive devices of this invention work in combination with the barrier layers on the roof to provide a leak detection system for the roof, that is, the benefit of the devices of the instant invention can only be realized if there is present above the surface of the deck, a water or air barrier film or layer. Such benefit will become apparent in the detailed discussion regarding the invention set forth below.
One object of the instant invention is to provide a penetrating device in combination with a barrier layer in a lamellar roof assembly that can be used as a means of localizing leaks in a lamellar roof system by allowing water to accumulate in specific localities in the lamellae of the roof and to allow limited amounts of water to pass from that accumulation in any lamellae of the roof system downwardly, and a further object of this invention is to provide a means of localizing leaks that will allow for the passage of only a limited amount of air from the interior to the roof assembly which is then allowed to pass through the roof system to the outside.
It is another object of the instant invention is to provide the simplest mechanism possible to provide the maximum holddown to maintain a deck system by a fastener.
It is yet another object of this invention to provide a method of manufacturing and repairing roofs such that the roof is susceptible of having localization of water from leaks in the water impermeable membranes, and is susceptible of having leak detection capabilities.
It should be noted that the devices and methods of this invention are especially useful for re-roofing over old lamellar roof systems because it allows one to re-insulate right over the old roof and use the devices of the instant invention for either leak detection, or fastening the whole into place over the old roof and then applying an integral water-impermeable membrane over the new insulation. This system allows one to re-roof a building without tearing into the old roof while using the old roof barriers as the barrier layer in the instant method.
The basic concept of the penetrating devices of the instant invention in order to be useful in the methods described herein is to have an opening from the upper layers of the roof assembly through the roof deck provided by the device. This opening can be between a hole that runs through the roof assembly into and through the supporting deck, and the effective diameter of the shank of such a penetrating device or it can include a device that has an opening through its long axis that runs from the device's uppermost end to the extreme lower end of the device.
For example, the diameter of the cutting point for a self-tapping screw and the shank diameter, and the thread diameters, can be adjusted to allow an opening between the hole in the deck and the shank of the screw to allow passage of limited amounts of water and air while adjusting the thread diameter and the hole in the deck diameter to provide securement or, in the case of a device of this invention where fastening is not required, the shaft of such a device simply has a groove or cut (opening) running the length of the shaft of the device, or yet, another embodiment of the openings in the devices of this invention is the device which has a center bore from its topmost end to the lower most end.
The self-tapping screws described above are called piercing screws, owing to the fact that they do not usually require pre-drilled holes for use because they pierce the metal deck of the roof and make their own hole for entry. These screws generally have threads along the most of the entire length of their shanks which assist the screw in maintaining it's position in the metal deck, i.e. the threads are designed to secure the screw.
Metal decks are normally twenty-two gauge steel and primarily, metal screws which are used to hold down roof systems are manufactured out of various metal alloys in an attempt to provide strength along with the self-tapping capabilities, and provide some corrosion resistance, generally by coating the screws prior to use, or by manufacturing the screws from special metal alloys. The penetrating devices are generally stronger than the substrate to which they are applied. Failure of these devices occurs in the pull-out from the substrate rather than destruction of the screw itself, which screws are nominally 1/8 to 1/4 of an inch in diameter for most roof systems, 3/16 being the most preferred. A weakness of a roof system that is frequently observed is at the top side where the materials, such as insulation, or roofing membranes, tear through the heads and washers of such devices causing the materials to be torn off the top of the roof system. The self-tapping characteristics of the screw means they can be installed in one operation, that is, the entire roof system is laid down in its multiple layers, and then fastened with a pattern of the screw type devices by penetrating from the top layer and forcing the screw through the roof deck for securing the entire roof system.
Penetrating devices having the configuration of anchor bolts are also generally known which consist of a bolt or stem which is threaded, has a cap or head portion on one end, and an expandable nut or toggle on the opposite end whereby after insertion through a preformed opening, the nut or toggle is twisted on the threaded bolt or stem and expands as the device is tightened up from above the roof to secure the materials between them. These toggle bolt type of penetrating devices are also useful in the fastening of roofs and for leak detection in that their threaded shanks can be continuously cut to give the same effect as that found in the metal devices of the instant invention.
Yet another type of penetrating device is a device which is simply a hollow plug, manufactured from plastic or metal, whose primary function would be as a leak localizer, without any fastening capability associated with the device. Thus, the primary function of such a plug would be to control the passage of moisture from the top of the plug, to the interior of the building, by having a hollow tube of a certain diameter to control the flow.
Thus, almost any penetrating device can be used in the instant invention, provided it has a water leak capability, and in the cases where fastening is required, it has fastening capabilities.